Process for preparing soap bars containing urea



United States Patent 3,507,797 PROCESS FOR PREPARING SOAP BARSCONTAINING UREA Bibhuti Ranjan Mazumder, Malabar Hill, India, asslgnorto Lever Brothers Company, New York, N.Y., a corporation of Maine NoDrawing. Filed Mar. 17, 1967, Ser. No. 623,836

Int. Cl. Clld 9/26, 9/30, 15/04 US. Cl. 252110 11 Claims ABSTRACT OF THEDISCLOSURE The bar provides a cooling sensation on'the'skin'when used.

This invention relates to toilet bars that provide a cooling sensationon the skin when used.

It is well-known that urea when handled in water has a cooling eifect onthe skin because of its ready solubility and high endothermic heat ofsolution. However, the simple incorporation of urea into toilet barswhether based on soap or non-soap detergent, does not give asatisfactory product. The resulting bar tends on storage to developslight opaque crystals on the surface or to manifest a gritty sandyfeel; sometimes both defects are found together. Also, on occasion,despite the inclusion of a high proportion of urea, the cooling effectis disappointingly slight.

It has been discovered that the above defects .can be reduced or removedalmost altogether and bars of a satisfactory appearance can be preparedif certain critical requirements regarding the composition of theurea-based bar and its preparation are observed. These criticalrequirements are set out below. (All references to percentages in thisspecification are to percentages by weight of the bar.)

The bar contains from 35-60% urea;

from -50% of an alkali-metal, ammonium or subsituted ammonium soap ofthe kind conventionally used in toilet bars and from 7-15% of asaturatedQ-C aliphatic The amount of urea preferably contained in thetoilet bar is 45-50%, the amount of alkali metal, ammonium orsubstituted ammonium soap contained in the toilet bar is preferably30-40% and the amount of saturated C -C aliphatic monocarboxylic acidpreferably contained in the toilet bar is 9-11%. It is also preferred toinclude in ice the toilet bar from l-4%, particularly 2-3%, or analkalimetal dihydrogen phosphate.

The term alkali-metal in this specification is to be taken as referringto sodium or potassium. The term substituted ammonium soap refers to asoap that is made with the aid of a substituted amine such asmonoethanolamine, diethanolamine, triethanolamine, monopropanolamine,dipropanolamine and tripropanolamine. The term conventionally used intoilet bars refers to a soap made from a fat charge wherein apredominating proportion of the acid or acid residue is a saturated orunsaturated aliphatic C -C monocarboxylic acid. The term saturated orunsaturated aliphatic C -C monocarboxylic acid refers to n-undecylicacid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidicacid, 10-undecylenic acid, lauroleic acid, myristoleic acid, palmetoleicacid, petroselenic acid, oleic acid, elaidic acid and linoleic acid.Particularly preferred acids include lauric acid, myristic acid,palmitic acid and stearic acid.

A minor proportion of a non-soap detergent can optionally be included.The remainder of the toiler bar consists of moisture and additivesnormally included in toilet bars if desired, such as perfumes,colourants, opacifying agents,

fluorescers, stabilisers, anti-oxidants, germicides, skin conditionersand emollients.

A feature of the bars of the invention is their low pH in comparisonwith conventional toilet soap bars, namely pH 7.7-8.3.

The critical nature of the above components and limits is seen from thefollowing Table I wherein the soap was prepared by neutralisation offatty acid by alkali. The bars were prepared observing the criticalprocessing requirements of the following paragraphs.

An aqueous solution or dispersion of the components that are to be usedin the manufacture of the toilet bar is formed and subsequently heatedat a temperature of between C. and C. until the water content of theheated system reaches the desired level (generally 2-4% The mass thusobtained is cooled and any heat sensitive components (such as perfume)added. The toilet bar is formed by conventional techniques includingmilling, plodding and stampling of the cooled mass. The essentialcomponents of the solution or dispersion are urea, fatty acid and soapand of these the soap can either be used as such or can be formed insitu by the partial saponification of the fatty acid with an appropriatealkali. The weights of the essential components are chosen so that thefinal composition of the toilet bar corresponds to that defined above inthis specification. To avoid decomposition of the urea during theheating stage the temperature is not allowed to rise above 105 C.; if atemperature of 95 C ,isnotattained a granulated product results. V a

An enhancement of the cooling effect can be achieve by increasing theproportion of fatty acid and decreasing the proportion of soap. Adecrease in the cooling effect is achieved by increasing the proportionof soap. A decrease in the proportion of fatty acid leads to thedevelopment of a sandy feel and chalky appearance of the bar. 7 Thesefacts are consistent with the theory that the basic structure of thetoilet bars of the invention is a ureafatty acid inclusion compound(formed in the heating step) stabilisedby soap. According totheliterature, the urea-inclusion compound should have a hexagonalstructure and additional urea molecules are attached to the soapmolecules by hydrogen bonding.

TABLE I Ingredients (in grams) Remarks Mono sodium di- Stearic LaurieSodium Potassium hydrogen Cooling Ref. Urea acid acid hydroxidehydroxide phosphate Perfume eileet pH Grittiness Keeping property A 1 4630 1 2. 5 5 Very little 8. 3 Sandy feeling.. Developed white coatingduring storage, no moisture absorption. B 46 5 1 2. 5 5 More cooling 7.8 Practically No white coating than A. absent. but absorbed moisture. C49 40 6 2 2.5 5 Practically 8.0 do Developed sandy no cooling. granuleson the surface of the bar on storage.

D 61 30 4 2 2. 5 5 Very slight 8. 1 Slight sandy Developed needlefeeling. shaped crystals on the surface of the bar.

E 35. 5 22 32. 5 4. 5 2 2. 5 1 No cooling 7. 7 Practically Absorbed lotof effect. absent. moisture on storage.

F 43 15 32. 5 4. 5 2 2. 5 5 Slight cooling--. 7. 8 .do Absorbed lot ofmoisture.

G 48 10 32. 5 4. 5 2 2. 5 5 Good 8. 0 d0 Good slight moistureabsorption.

H 51 7 32. 5 4. 5 2 2. 5 5 Not bad 8.0 .do Slight moisture absorption.Developed granules on storage.

I 48 16 27. 5 4 1. 5 2. 5 7. 8 ...do Absorbed moisture on storage.

I 48 12. 5 30 4 2 2.5 7.8 do Do.

K 48 7 5 2 2. 5 8. 1 Practically ab- Developed pow- I sent; good slip.dery coating on the surface.

L 48 4 37. 5 6 1. 5 2. 5 5 Very little 8. 0 do Developed needle shapedcrystals on the surface of the bar.

This her also contained 13 g. sodium lauryl sulphate.

It will be seen that bars outside the scope of the invenand a thickcoating of a white crystalline material covered tion are inferior (forexample, bars A, C, D, E and L) to 35 the 'surface of the bar.

bars within the scope of the invention v(for example, bars B, F, G, H,I, J and K) and of these latter the bars of composition at theextremities of the given limits are inferior to those within the limits.

The above shows that heating of the mixture of fatty acid and urea isnecessary for avoiding crystallisation.

What is claimed is:

1. A toilet bar containing by weight of the bar The invention is furtherillustrated by the following ex- 40 from 35% to urea; amples in whichthe composition and properties of toilet from 20% to 50% of a soapselected from the group bars according to the invention are given. Thebars were consisting of alkali metal, ammonium, monocthanolpreparedobserving the critical processing requirements ammonium,diethanolammonium, triethanolammoniindicated earlier. um,monopropanolammonium; dipropanolammoni- Ingredients (in Grams) RemarksMono sodium di- Stearic Laurie Sodium Potassium hydrogen Cooling Ex.Urea acid acid hydroxide hydroxide phosphate Perfume eflect pHGrittiness Keeping property 1 48 10 32. 5 4. 5 2 2.5 5 GOOd 8.0Practically Good; slight moisabsent. ture absorption.

2 48 9 31. 25 4. 25 2 2. 5 1 d0 8. 1 Practically no Do.

grittiness,

good slip 3 49 9 32 4.5 2 2.5 1 Moderate; el- 8.1 .do Do.

most same as Ex. 2

4 47 8 35 5 2 2.5 do 8.0 Practically no Slight moisture grittiness;absorption.

slip better than Ex. 3. 5 A 46. 45 9. 5 33. 4. 75 2 2. 5 1 d0 8.1Practically no Do.

grittiness;

best slip.

1 Also included 2 g. beeswax.

The preparation of Example 5 was repeated using the following procedure.

Stearic acid (9.5 g.) and lauric acid (33.75 g.)'were melted together ina beaker. To this was added an aqueous solution of sodium hydroxide(4.75 g.), potassium hydroxide (2.0 g.) and monosodium phosphate (2.5g.). The mass was mixed thoroughly and dried at 105 C. in an oven tillthe moisture content was reduced to about 3 percent. This was cooled,mixed with urea (46.45 g.) and perfume .(1.0 g.), milled, plodded andstamped. On the day of stamping, the surface of the bar was quite smooth2 Also included 0.05 titanium dioxide.

um, or tripropanolammonium soaps of fatty acids having from about 10 -toabout 20 carbon atoms, and mixture thereof, and

from 7% to 15% of a saturated fatty acid selected from the groupconsisting of unsubstituted monocarboxylic acids having from about 10 toabout 20 carbon :atoms, and mixtures thereof. the group consisting ofhaving from about 10 to about 2. A toilet bar according to claim 1containing from 4550% of urea.

3. A toilet bar according to claim 1 containing from but, within two orthree days, the whole bar swelled up 75 30-40% of the said soap.

4. A toilet bar according to claim 1 containing from 9-l1% of saidstaurated fatty acid.

5. A toilet bar according to claim 1 in Which the soap is prepared insitu by partial saponification of a fatty acid selected from the groupconsisting of saturated C C unsubstituted monocarboxylic acids andmixtures thereof.

6. A toilet bar according to claim 5 containing from 45-50% urea.

7. A toilet bar according to claim 5 containing from 30-40% soap.

8. A toilet bar according to claim 5 containing from 9-1 1 of saidsaturated fatty acid.

9. A toilet bar according to claim 1 containing from 14% of an alkalimetal dihydrogen phosphate.

10. A toilet bar according to claim 1 containing from 2-3 of an alkalimetal dihydrogen phosphate.

11. A toilet bar according to claim 1 which has a pH of 7.7-8.3.

References Cited UNITED STATES PATENTS 0 1,716,347 6/1929 Riehl et a1252132 XR 2,374,187 4/1945 Flett 252-152 2,665,256 1/1954 Barker 2521S22,838,480 6/1958 Swern et a1. 26096.5

10 MAYER WEINBLATT, Primary Examiner D. L. ALBRECHT, Assistant ExaminerUS. Cl. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. v 797Dated April 1970 Inventor(s) Bibhuti Ranjan Mazumder It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Column 2, line 43, "stamping" is misspelled.

Table I, line 2, "grams" should read -Grams--.

Column 4, line 66, "mixture" should read --mixtures--.

Column 4, lines 67-71 inclusive. This entire passage should be deletedand corrected to read:

-from 7% to of a saturated fatty acid selected from the group consistingof unsubstituted monocarboxylic acids having from about 10 to aboutcarbon atoms, and mixtures thereof, which is prepared by a toilet barforming process including the step of heating an aqueous solution ordispersion of the above components to a temperature between and C. untilthe heated mass has a water content of between 2 and 4% w/w.--

SIGNED AND QEAIED Afloat:

Edwin-Wk tr :1, JR, E commissioner of Patents FORM PO-IOSO -69)uscoMuhDc gonad," e In. aovlnmnn nmmuc omcc nu o-au-au

